Polyketones derived from diphenyl ether and terephthaloyl and isophthaloyl chlorides by Friedel-Crafts synthesis are known from, for example, U.S. Pat. Nos. 3,065,205; 3,441,538; 3,442,857; 3,516,966; 3,637,592; 3,666,612; 3,767,620. These polyketones possess desirable and useful chemical and physical properties. In this regard, U.S. Pat. No. 3,767,620 states the following in column 1, lines 23 to 28:
"Their good electrical properties, coupled with resistance to thermal oxidative and hydrolytic degradation, made them good candidates for electrical insulation, but these polymers tend to degrade and undergo decomposition during attempts to extrude them." PA1 "However, I have now discovered that when the terminal group on either or both ends of each polymer chain is a phenoxy (or other nucleophilic) moiety having a para position available for reaction then, in highly acid media such as hydrogen fluoride/boron fluoride mixtures, a preferred polymerization reaction media, another heretofore unknown branching reaction occurs. It is believed that such branching results from the reaction of the phenoxy (or other nucleophilic) groups (presumably activated, i.e., protonated by the acid media) with carbonyl groups in the polymer itself leading, I believe, to the formation of trisaryl carbonium salts. In addition to the deleterious effect of branching per se on processability, such salts are thermally very unstable and lead to degradation and discoloration in the polymer when molten". PA1 z is halogen, alkyl or alkoxy PA1 4--nitrodiphenyl ether PA1 4--phenoxybenzophenone PA1 4--phenoxydiphenyl sulfone PA1 anisole PA1 fluorobenzene PA1 chlorobenzene PA1 biphenyl PA1 toluene. PA1 benzoyl chloride PA1 p-fluorobenzoyl chloride PA1 p-chlorobenzoyl chloride PA1 p-methoxybenzoyl chloride PA1 benzene sulfonyl chloride PA1 p-chlorobenzene sulfonyl chloride PA1 p-methylbenzene sulfonyl chloride PA1 4-benzoyl-benzoyl chloride PA1 (i) at least one electrophilic aromatic diacyl halide of the formula EQU YOC--Ar--COY PA1 where --Ar-- is a divalent aromatic radical such as phenylene, diphenylether-4,4'-diyl, diphenyl-4,4'-diyl, naphthalene, and the like, Y is halogen such as chlorine, bromine or iodine with chlorine being preferred, and COY is an aromatically bound acyl halide group, which diacyl halide is polymerizable with at least one aromatic compound of (a)(ii), and PA1 (ii) at least one aromatic nucleophilic compound of the formula EQU H--Ar'--H PA1 where --Ar'-- is divalent aromatic radical such as diphenylether-4,4'-diyl, 2,7-dibenzofurandiyl, diphenyl-4,4'-diyl, diphenylmethane-4,4'-diyl, and the like, and H is an aromatically bound hydrogen atom, which compound is polymerizable with at least one diacyl halide of (a)(i), and PA1 where --Ar"-- is a divalent aromatic radical such as diphenylether-4,4'-diyl, 2,7-dibenzofurandiyl, diphenyl-4,4'-diyl, diphenylmethane-4,4'-diyl, and the like and H is an aromatically bound hydrogen atom, Y is as defined above, and COY is an aromatically bound acyl halide group, which monoacyl halide is self-polymerizable, and
U.S. Pat. No. 3,767,620 attributes the melt instability of the polyketones produced by Friedel-Crafts polymerization to a high percentage of 9-phenylenexanthydrol end groups. The chemical reduction of 9-phenylenexanthydrol end groups to the corresponding 9-phenylenexanthene groups is stated in the patent to provide a polyketone with improved thermal stability after the reduction.
U.S. Pat. No. 4,247,682 describes polyarylketones and polyaryl sulfones having good melt stability. These polymers are prepared by a Friedel-Crafts condensation polymerization. The polymerization is carried out in solution and is homogenous. The patent states the following in column 1, lines 48 to 64:
The polymers in U.S. Pat. No. 4,247,682 are capped at each end by a nucleophilic or electrophilic capping agent. The nucleophilic capping agents are described as having the general formula: ##STR1## where X is preferably --O-- or a covalent bond and Y is CN and NO.sub.2. The electrophilic capping agents are described as having the general formula Ar"COZ or AR"SO.sub.2 Z with Z being OH, halogen or OR where R is alkyl, and Ar" being phenyl, etc., either unsubstituted or substituted with one or more electron withdrawing substituents such as halogen, nitro or cyano.
However, the polymerization in U.S. Pat. No. 4,247,682 is carried out in anhydrous hydrogen fluoride with boron trifluoride as the catalyst and is thus a homogeneous process. Further, the double end capping is carried out in hydrogen fluoride solution.